About Joining Walls
Use the Join tool to connect two intersecting walls in a sheet metal part. You can trim the nonintersecting portions of the walls, add a bend and bend relief at the intersection, as well as flip the orientation of the intersecting walls.
Keep in mind the following points when joining walls:
The intersecting walls must be planar.
The driving and offset sides of the walls to join are swapped automatically, if necessary, to match the sides of the earliest wall created.
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Swapping the driving and offset sides can change the location of sheet metal cuts located on the walls. For example, when you reorder a Join feature in the Model Tree and reinsert it before a cut that references an automatically swapped side, the location and the geometry of the removed material may change.